How are Ahab's actions blasphemous?

Ahab as a Blasphemous Figure

A major assumption that runs through Moby Dick is that Ahab's quest against the great whale is a blasphemous activity, even apart from the consequences that it has upon its crew. This blasphemy takes two major forms: the first type of blasphemy to prevail within Ahab is hubris, the idea that Ahab thinks himself the equal of God. The second type of blasphemy is a rejection of God altogether for an alliance with the devil. Melville makes this point explicit during various episodes of the novel, such as the instance in which Gabriel warns Ahab to "think of the blasphemer's end" (Chapter 71: The Jeroboam's Story) and the appraisal of Ahab from Peleg in which he designates him as an ungodly man (Chapter 16: The Ship).

The idea that Ahab's quest for Moby Dick is an act of defiance toward God assuming that Ahab is omnipotent first occurs before Ahab is even introduced during Father Mapple's sermon. The lesson of the sermon, which concerns the story of Jonah and the whale, is to warn against the blasphemous idea that a ship can carry a man into regions where God does not reign. Ahab parallels this idea when he compares himself to God as the lord over the Pequod (Chapter 109: Ahab andStarbuck in the Cabin). Melville furthers this idea through the prophetic dream that Fedallah tells Ahab that causes Ahab to conclude that he is immortal.

Nevertheless, a more disturbing type of blasphemy also emerges during the course of the novel in which Ahab does not merely believe himself omnipotent, but aligns himself with the devil during his quest. Ahab remains in collaboration with Fedallah, a character rumored by Stubb to be the devil himself, and when Ahab receives his harpoon he asks that it be baptized in the name of the devil, not in the name of the father.